二维不规则形状发热型缺陷的红外识别算法

对带有自身发热型缺陷的试件建立二维传热模型,利用有限元法进行求解,研究试件表面的温度分布规律,并根据共轭梯度法提出根据试件外表面红外测温,定量识别发热型内部缺陷边界轮廓的方法.数值实验证明了算法的有效性.对所研究缺陷类型,导热系数较小的试件识别精度较高;温度测量误差、测温点数目及缺陷轮廓初值假设对识别结果的影响可以忽略;检测表面最大温差越大,识别精度越高.

Thermographic Identification Algorithm of Two-dimensional Irregular-shaped Self-heating Subsurface Defects

A two-dimensional heat transfer model is built and solved with finite element method to study temperature distribution on outer surface of a test piece with a self-heating subsurface defect. Based on conjugate gradient method, an algorithm is proposed for identification of subsurface defect with temperature on the outer surface of the teat piece measured with an infrared imager. Effectiveness of the method is validated by numerical experiments. It is concluded that the method identifies serf-heating defects with high precision for test pieces with small thermal conductivity. Effect of temperature measurement error, number of temperature measurement point and initial defect boundary guess on defect identification can be neglected. The greater the maximum temperature difference on outer test piece surface is, the higher precision of identification is.